This invention relates generally to a pipette device, and more particularly to a pipette device which makes it possible to perform the operations of sucking a liquid (that is, introduction of a liquid into a tip), discharging the same (that is, removal of the liquid from the tip) and removing a tip simply by operating a single electrical switch.
There have been known pipette devices which comprise a housing graspable with an operator's single hand within which there are provided a cylinder, a plunger or piston adapted to operate in the cylinder to suck a liquid and then discharge the same, an operating rod secured to the upper end of the plunger, and a return spring for exerting upward bias force onto the operating rod, whereby the respective operations of sucking a liquid, discharging the same and removing a tip are effected by manipulation of an operating knob secured to the upper end of the operating rod by an operator's finger. With such a known pipette device, when it is desired to suck a liquid, the operating knob is lowered by a certain distance against the force of the return spring and then released so as to allow the plunger to be returned upwardly by the force of the return spring. When it is desired to discharge the liquid thus sucked, the operating knob is lowered again. When it is desired to remove the tip, a separate knob provided for this purpose is depressed.
It is troublesome to manually operate such an operating knob.
Further, such a prior art device as mentioned above has the disadvantage that reproducibility or consistency of performance is not good because the operating knob is operated manually and slight changes in sucking speed are caused by variations in finger pressure durig the sucking operation thereby causing variations in the volume of the liquid sucked.
Further, in most cases, such devices of this kind are used by female operators and therefore there is risk of inducing a work-related disorder such as tenonitis or the like as a result of the operator's finger fatigue if a lot of objects are to be sampled.